The purpose of this proposal is to generate data on the prevalence of antibiotic resistance genes in the bacterial flora from periodontally diseased individuals and determine if DNA probes for specific antibiotic resistance genes can be used to test plaque samples taken directly from diseased sites. The specific aims are the following: l. Characterize the antibiotic resistance determinants carried by the subgingival microflora isolated from 2- 3 early onset periodontitis patients with a history of antibiotic therapy. The target organisms will include: Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter (Wolinella) recta, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, as well as, the normal flora species which grow on antibiotic supplemented plates. 2. Determine the efficacy of screening subgingival plaque samples for the presence of antibiotic resistance genes using DNA probes. The material will be screened with DNA probes coding for tetracycline, macrolides plus clindamycin and metronidazole antibiotic resistance genes. Both normal subjects and patients with periodontitis will be sampled. Cultures, from probe positive sites, will be taken to allow isolation and identification of periopathogens. We will determine if there is a correlation between the direct plaque hybridization and hybridization of the isolated bacteria with the various DNA probes. The antibiotic resistant, normal flora will also be examined. Information on the status of antibiotic resistant organisms from plaque samples could be used in planning and prescribing the patient's, antibiotic treatment. 3. Screen the available periodontal pathogens with the DNA probes for tetracycline, macrolides, lincosamides, clindamycin, and metronidazole resistance genes. 4. Correlate hybridization with a specific antibiotic resistance DNA probe and the organisms ability to grow in the presence of that antibiotic. Determine if the antibiotic resistance genes can be transferred to the recipients during conjugation. The information we generate from this grant will provide needed molecular tools, such as potential transposons for transposon mutagenesis, to further study the pathogenic properties of a variety of periodontal pathogens.